1. Field of the Invention
The present invention relates to anchor piles that are used for subsea installations. More particularly, the present invention the relates to anchor piles that include mechanisms for achieving the installation of the anchor pile. More specifically, the present invention the relates to anchor piles that have a rotatable auger for the purpose of drawing the anchor pile into the subsea soil. Additionally, the present invention relates to anchor pile assemblies and methods of connecting the anchor piles together.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Offshore structures, vessels and floating rigs require anchoring points to safely moor or position them in situ, or to offer resistance to allow rig repositioning or movement. Known anchoring systems use fluke, gravity, suction-type anchors, or driven foundation piles to provide resistance to lateral or tension loads. Fluke, gravity and suction anchors provide limited and unquantified pull-out resistance, and have been installed in a variety of ways, e.g. by dragging flukes into the seabed, or by suctioning structures into the seabed.
Shallow water systems may make use of piles driven and/or drilled into the ocean floor to provide resistance to compression, tension or lateral loads. However, in deep sea and ultra-deep environments, increased installation costs limit the use of subsea pile driving hammers for pile foundation. As is well known in the art, a pile driver system operates through the repeated striking of a foundation element with loads or forces of high magnitude. This advances the foundation elements into the ground in increments. The kinetic energy output of a pile driver is a function of its ram mass and the velocity of the ram at impact. Pile driving is accomplished through the transmission of the kinetic energy of the pile driver to the pile to overcome resistance and loss forces and impart a displacement to the pile. The hammering systems are efficient only up to a certain length of pile. Once a critical depth has been reached, the subsea hammering process becomes inefficient. Additionally, the subsea hammers require expensive support surface equipment before operation.
In the past, various patents have issued relating to such subsea anchor piles and methods of installation. For example, U.S. Pat. No. 4,637,757, issued on Jan. 20, 1987 to K. M. Aagaard, teaches a barbed anchor pile. This anchor pile has horizontally placed barbs so as to allow the barbs to be driven into the seafloor. Once the pile is buried to a predetermined depth, the barbs are spread outwardly into the surrounding soil to ensure that the pile will not be pulled out by uplift loads.
U.S. Pat. No. 6,129,487, issued on Oct. 10, 2000 to Bermingham et al., shows an underwater pile driving tool for the purposes of installing anchor piles in a ground formation that is submerged under a body of water. A hammer body is fixedly supported in axial alignment with the head of a pile that is to be driven and carries a reaction body guided for movement thereon in a direction that is axial to the pile. The hammer body and reaction body define opposed first and second ends of an expansion chamber. A pyrotechnic charge is initiated to create a rapidly expanding volume of high pressure gas in the expansion chamber to generate a downwards pressure force pulse to drive the pile. This causes equal and opposite upwards pressure force pulse to be applied to the reaction body.
U.S. Pat. No. 6,719,496, issued on Apr. 13, 2004 to W. H. Von Eberstein, shows an ROV-installed suction pile. This suction pile has flood valves opened on the top thereof so as to allow the suction pile to be off-loaded from the anchor boat and lowered to the sea floor. The suction pile anchor is set down and the rate of feed is adjusted to match the rate of self-penetration. An ROV with pump capability closes the flood valves on the top of the suction pile and attaches to the pumping port of the suction pile. The pump of the ROV operates to draw down the suction pile to a full depth and brings the first load line connection and the attached first end of the load line well below the mudline while the second load connection at the second end of the load line is supported above the mudline. The ROV disconnects from the pump port and connects a mooring line to the second load connection.
U.S. Pat. No. 7,140,319, issued on Nov. 24, 2006 to R. V. Raines, shows a pile anchor having external vanes. This pile anchor is an elongated hollow member. The external vanes are longitudinally disposed thereon. The external vane helps to maintain the heading and bearing of the anchor during the installation process and also to enhance the pile anchor's holding capacity.
U.S. Pat. No. 5,704,732, issued on Jan. 6, 1998 to E. E. Horton, provides a deep water piling and method of installing or removing. This device is intended to eliminate the need for underwater hammers or pile drivers. The pile is a hollow tube that is open at the lower end and provided with a fitting at the upper end for attachment to a lowering pipe. The fitting at the upper end also allows for fluid communication between the lowering pipe and the pile. Air is injected into the lowering pipe draws water from the lowering pipe and pile. This creates a hydrostatic pressure differential whereby the greater pressure on the outside of the pile head forces the pile into the sea floor. Removal of the pile may be accomplished by injecting high pressure water into the pile through the pile head. The high pressure water injection aids in overcoming the hydrostatic pressure on the outside of the pile head.
It is an object of the present invention to install anchor piles in subsea soils.
It is another object of the present invention to provide for the installation of longer piles in deeper water.
It is another object of the present invention to provide a stronger anchor than can be installed in association with subsea hammers.
It is sill a further object of the present invention to provide an anchor pile that is smaller and stronger than conventional piles in ultra-deep water.
It is still a further object of the present invention to provide an anchor pile that can be effectively installed by an ROV and with minimal surface installations and equipment.
It is another object of the present invention to provide an anchor pile that allows for installation from a small, inexpensive vessel.
It is another object of the present invention to allow for installation of a long pile by stacking several shorter piles one over the previous installed pile and repeating this procedure until the desired pile length is reached, all from a low-cost installation vessel.
It is another object of the present invention to provide an anchor pile assembly whereby desired lengths of anchor piles can be connected in end-to-end relationship in a subsea location.
It is a further object of the present invention to provide a method of connecting anchor piles in end-to-end relationship in a convenient and simple manner.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.